5 The Muscular System

5

The Muscular

System

Lesson 5.1: Muscle Tissue Categories and Functions

Lesson 5.2: Skeletal Muscle Actions

Lesson 5.3: The Major Skeletal Muscles

Lesson 5.4: Common Injuries and

Disorders of Muscles

Chapter 5: The Muscular System

Lesson 5.1

Muscle Tissue Categories and Functions

Muscle Tissue

• categories

– skeletal

– smooth

– cardiac

• functions

– behavioral properties

– tension and types of skeletal muscle contractions

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Muscle Tissue Categories

• skeletal

– voluntary

– striated

• smooth

– involuntary

– no striations

• cardiac

– involuntary

– striated

– intercalated disks



Muscle Tissue Categories



Skeletal Muscle Organization

• sarcolemma and endomysium surrounds the muscle fiber

• perimysium bundles groups of muscle fibers to make up a fascicle

• epimysium encloses several fascicles to make up a muscle

• aponeurosis connects muscle to other tissues



Skeletal Muscle Organization



Review and Assessment

True or False?

1. Smooth muscle is voluntary.

2. Cardiac muscle has branching fibers.

3. Smooth muscle is multinucleate.

4. Perimysium wraps fascicles to make a muscle.

5. Endomysium surrounds the muscle fibers.



Behavioral Properties of Muscle

• extensibility–stretch

• elasticity–snap back

• irritability–respond

• contractility–shorten



Muscle Tissue Functions

• tension and types of skeletal muscle contraction

– agonist–moves bone

– antagonist–opposes the movement of the agonist



Concentric Contraction

• agonist contracts, antagonist relaxes



Eccentric Contraction

• agonist contracts while lengthening, antagonist relaxes



Isometric Contraction

• both agonist and antagonist contract




Match these words with 1 – 5 below: extensibility, elasticity, irritability, contractility, agonist, antagonist.

1. respond

2. opposes movement

3. stretch

4. shorten

5. causes movement




Lesson 5.2

Skeletal Muscle Actions

Skeletal Muscle

• the motor unit

• skeletal fiber types

• muscular strength, power, and endurance



The Motor Unit

• group of muscle fibers under the control of one motor neuron



Generating Action Potentials

• acetylcholine crosses the synaptic cleft at the neuromuscular junction

• depolarization takes place on muscle fiber

• action potential begins



Contraction of the Sarcomeres

• sarcomeres shorten by actin filaments sliding along myosin filaments



Maximum Tension and Return to

Relaxation

• action potential always causes entire motor unit muscle fibers to contract

• all-or-none law




True or False?

1. An action potential causes one half of the fibers in the motor unit to contract.

2. Acetylcholine crosses the synaptic cleft at the neuromuscular junction.

3. The sarcomeres lengthen by myosin filaments sliding over actin filaments.



Skeletal Muscle Fiber Types

• slow-twitch

• fast-twitch

– type IIa

– type IIb



Skeletal Muscle Fiber Architecture

• parallel fiber arrangements

– fusiform (biceps brachii)

– bundled (rectus abdominis)

– triangular (pectoralis major)

• pennate fiber arrangements

– unipennate (extensor digitorum)

– bipennate (rectus femoris)

– multipennate (deltoid)



Muscular Strength

• rotary force that muscles can produce at a joint

– the maximum weight you can lift is a measurement of muscular strength



Muscle Power

• force x velocity

– how fast you can sprint is a measurement of muscle power



Muscle Endurance

• muscle tension/time

– how far you can run is a measurement of muscle endurance




Match these words with 1 – 5 below: muscle endurance, muscular strength, muscle power,

Type I, Type IIb.

1. force x velocity

2. muscle tension/time

3. rotary force that muscles can produce at a joint

4. slow twitch, slow fatigue

5. fast twitch, fast fatigue




Lesson 5.3

The Major Skeletal

Muscles

The Major Skeletal Muscles

• directional motions

• head and neck muscles

• trunk muscles

• upper limb muscles

• lower limb muscles



Skeletal Muscle Attachments

• origin

– fixed end of a muscle

• insertion

– movable end of a muscle



Sagittal Plane Movements

• flexion

• extension

• hyperextension

• dorsiflexion

• plantar flexion



Frontal Plane Movements

• abduction

• adduction

• inversion

• eversion

• radial deviation

• ulnar deviation



Transverse Plane Movements

• medial rotation

• lateral rotation

• pronation

• supination



Multiplanar Movements

• circumduction

• opposition




True or False?

1. Circumduction is a multiple plane movement.

2. Supination is a multiple plane movement.

3. The insertion is the fixed end of a muscle.

4. Extension is a sagittal plane movement.

5. Adduction is a frontal plane movement.



Head and Neck Muscles



Head and Neck Muscles

• Frontalis: raises eyebrows, wrinkles forehead

• Orbicularis oculi : closes eyes, enables squinting

• Nasalis: modifies size of nostrils

• Orbicularis oris : closes lips, kissing motion

• Zygomaticus : the “smiling muscle”

• Platysma: pulls corners of mouth down, opens mouth wide

• Masseter : closes the jaw

• Temporalis: assists the masseter with closing jaw

• Sternocleidomastoid : flexion and rotation of head



Trunk Muscles



Trunk Muscles

• Pectoralis major : adduction and flexion of the arm

• Rectus abdominis : flexion/lateral flexion of trunk

• External oblique : flexion/lateral flexion/rotation trunk

• Internal oblique : flexion/lateral flexion/rotation trunk

• Trapezius : extension and hyperextension of head

• Erector spinae: extension/lateral flexion/rotation spine



Upper Limb Muscles



Upper Limp Muscles

• Deltoid : abduction, flexion, extension, and rotation of arm

• Latissimus dorsi : extension, adduction, and medial rotation of arm

• Biceps brachii : flexion of forearm

• Brachialis: flexion of forearm

• Brachioradialis: flexion of forearm

• Triceps brachii : extension of forearm



Lower Limb Muscles



Lower Limb Muscles

• Gluteus maximus : extension and lateral rotation of leg

• Gluteus medius : abduction and medial rotation of leg

• Iliopsoas: flexion of leg at hip

• Quadriceps : extension of leg at knee

• Hamstrings : flexion of leg at knee

• Sartorius : assists with flexion, abduction, and lateral rotation of thigh

• Gastrocnemius : plantar flexion, flexion of leg at knee

• Soleus : plantar flexion

• Tibialis anterior : dorsiflexion and inversion of foot




Match these words with 1 – 4 below: head, trunk, upper limb, lower limb.

1. temporalis

2. brachioradialis

3. external oblique

4. biceps femoris




Lesson 5.4

Common Injuries and

Disorders of Muscles

Muscle Injuries

• strain – overstretched muscle

– grade I, II, III

• contusion–bruised muscle

– myositis ossificans

• cramps – spasming muscle

• delayed onset muscle soreness – tear



Tendon Injuries

• tendinitis– inflamed tendon

• tendinosis– degeneration of a tendon

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Joint Injuries

• rotational injury at shoulder

• overuse of elbow

• shin splints

• whiplash



Muscle Disorders

• muscular dystrophy

• hernia




True or False?

1. Tendinitis is muscle strain.

2. A contusion is a bruise.

3. Whiplash is a joint injury.

4. A hernia is a tendon injury.

5. A strain is an over stretch of a tendon.



5 The Muscular System

The Muscular

System

Muscle Tissue Categories and Functions

Skeletal Muscle Actions

The Major Skeletal

Muscles

Common Injuries and

Disorders of Muscles

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5 The Muscular System

The Muscular

System

Muscle Tissue Categories and Functions

Skeletal Muscle Actions

The Major Skeletal

Muscles

Common Injuries and

Disorders of Muscles

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